包覆型α-Al_2O_3粉体的制备及表征

Preparation and characterization of coated α-Al_2O_3 powders

以平均粒径为22μm和0.5μm的α-Al2O3粉体为起始原料(以下分别简称Al2O3(C)和Al2O3(F)),分别以聚乙烯亚胺(PEI)和聚甲基丙烯酸铵(APMA)为聚合物电解质,采用非均相凝固法将Al2O3(F)颗粒均匀地包覆在Al2O3(C)粉体表面.重点考察了聚合物电解质的吸附时间、Al2O3(C)/Al2O3(F)的质量比、两种分子量的PEI对包覆型氧化铝粉体制备的影响.当Al2O3(C)/Al2O3(F)的质量比为1∶3,经过分子量约为60 000的PEI处理2 h的Al2O3(C)粉体表面均匀地包覆了Al2O3(F)颗粒(经APMA处理2 h).采用该包覆型粉体制备出片状多孔支撑体,其孔隙率为35.8%,平均孔径为2.9μm,纯水通量为205 m3/(m2.h.MPa).

Coated alumina powders were prepared by using α- Al2O3 with average particle size ot 22： μm and 0.5 μm as starting powders（hereafter mentioned as Al2O3 （C） and Al2O3 （F）, respectively） through heterocoag- ulation process was investigated.Al2O3 （F） particle was successfully coated on the surface of Al2O3 （C） by using ammonia polymethacrylate（APMA） and polyethylenimine（PEI） as polyelectrolyte dispersant, respectively. The effect of adsorption time of polyelectrolyte dispersant on the surface of alumina, the weight ratio of Al2O3（C）/ Al2O3（F） as well as the two PEI with different molecular weight on the result of coated powders was studied in detail. The optimal coating conditions was as follows： the weight ratio of Al2O3（C） to Al2O3（F） was 1：3, Al2O3（C） powder and Al2O3（F） powder was modified with PEI （MW = 60 000） and APMA for 2 h, respectively. Disk supports were prepared by using the coated alumina powders under the abovementioned optimal conditions and the property of such disk support was as follows, porosity： 35.8% ,average pore size： 2.9/μm, pure water flux： 205 m3/（m2·h·MPa）.